1. Field of the Invention
The present invention relates to an apparatus and a method for encoding and decoding data, and more particularly, to a differential pulse code modulation (DPCM) operation, a method of normalizing data, and a method and an apparatus for encoding and decoding data using the DPCM operation and the method of normalizing data.
2. Description of the Related Art
FIG. 1 is a block diagram showing the structures of a conventional apparatus for encoding data and a conventional apparatus for decoding data. Referring to FIG. 1, a conventional apparatus for encoding data includes a quantizer 100, a DPCM operator 110, and an entropy encoder 120. According to a conventional method for encoding data, input data are quantized with a predetermined number of bits in the quantizer 100 and are input into the DPCM operator 110. The DPCM operator 110 generates differential data by subtracting the current quantized data input from the quantizer 100 from previous quantized data and outputs the differential data to the entropy encoder 120. The entropy encoder 120 encodes the differential data into a bitstream using a predetermined entropy-encoding method.
Referring to FIG. 1, a conventional apparatus for decoding data includes an entropy decoder 130, an inverse DPCM operator 140, and an inverse quantizer 150. A bitstream, into which data are encoded, is input into the entropy decoder 130. The entropy decoder 130 outputs differential data inversely performing the process performed by the entropy encoder, and then the inverse DPCM operator 140 converts the differential data input from the entropy decoder 130 into quantized data and outputs the quantized data to the inverse quantizer 150. The inverse quantizer 150 inversely quantizes the quantized data input from the inverse DPCM operator 140 and then outputs decoded data.
However, since the aforementioned conventional method for encoding data only performs a simple DPCM operation so as to reduce the amount of data to be encoded and encodes data having a plurality of components without considering the characteristics of each of the x, y, and z components of the data, especially when the data are consecutively input, its encoding efficiency is not high enough.